Amphibious vehicle steering

ABSTRACT

An amphibious vehicle has retractable wheels ( 2, 3 ) attached to hubs ( 2 ), and a planing hull ( 10, 11, 3 ). Front wheels are arranged to be steered by a power assisted transversely mounted element ( 16 ), which may be a rack and pinion unit. The element may be linked to the wheels by links ( 14, 14′ ), which fold up to position ( 14″ ) when the wheels are retracted. Actuating rod ( 28 ) is mounted to said element, and arranged for transverse movement. A flexible coupling means, such as cable ( 34 ) and sleeve ( 36 ), connects rod ( 28 ) to a steerable part ( 42, 4 ) of a marine propulsion unit, to effect marine steering. Road and marine steering may be operable simultaneously. More than one front steered axle, and/or marine propulsion unit, may be fitted. The steering system is readily adapted to all kinds of power assisted steering, and also to “steer by wire”.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is the U.S. national phase entry ofPCT/GB04/001697 with an international filing date of Apr. 19, 2004 andclaims priority from GB Patent Application Serial No. 0309452.1, filedApr. 25, 2003.

FIELD OF THE INVENTION

The present invention relates to amphibious vehicle steering.

BACKGROUND OF THE INVENTION

Amphibious vehicles, hereafter “amphibians”, are frequently steered intheir land and marine modes by the same steering wheel. A simple form ofamphibian steering is shown in U.S. Pat. No. 5,727,494 (Caserta). InCaserta's proposal, a steering cable is arranged between a rearpropulsion unit and the inner shaft of the steering column, which thecable is wound around, and thence back to the marine propulsion unit.Whilst this is a simple arrangement, it is unsuitable for high speedplaning amphibians, where the force required to steer the propulsionunit is high. That is, the mechanical advantage of the Casertaarrangement is low. Where an automotive steering column is used, thereis a high risk that the steering cable according to Caserta willconflict either with the mechanism designed to ensure crushability ofthe steering column in an accident; or alternatively, with anytelescopic adjustment mechanism designed to ensure an ergonomic drivingposition.

In another proposal shown in U.S. Pat. No., 5,590,617 (Gere), thelinkages between the rear marine propulsion unit and the steeringarrangement at the front of the vehicle are bulky and heavy, at alocation at the front of the vehicle where weight has to be carefullycontrolled in a planing amphibian. Furthermore, the steering accordingto Gere is conformed so as to be operable in either a road mode or amarine mode. To allow this duality, the road steering system depends foroperation on the steering rack being held in place by pressurizedpneumatic rams. This is somewhat alarming from a safety viewpoint.

It is considered advantageous to have road and marine steering systemwhich can be operated simultaneously. This simplifies control systems,as there are less changes to be made in converting from road mode tomarine mode or vice versa. Also, when maneuvering at low speed in water,particularly to direct an amphibian to a slipway, the steering effect ofdependent road wheels may be at least as great as that of, for example,a steering nozzle attached to a jet drive. Furthermore, if both systemscan be operated together, there is no need for complex systems to ensurethat when one or the other system is switched in, it is always initiallycentered. Finally, there is a safety advantage, in that in the unlikelyevent of breakage or seizure of the steering cable, a second steeringsystem is available. In this context, it should be noted that the marinesteering is self-centering. In the absence of any control input orrestraint of movement, passage of water through the jet nozzle will tendto center the nozzle.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a steering system for aplaning plan amphibian in which the steering system is balanced, so thatpower assistance to the road steering matches the power assistancerequired to overcome the self centering centring tendency of the marinepropulsion unit running at high speed. Another object is to reduce thebulk of parts of the steering assembly in the region between the frontwheels, which have to retract to reduce water resistance in a planingamphibious vehicle.

According to the invention, there is provided an amphibious vehiclehaving retractable wheels and a planing hull, a marine propulsion unit,front wheels arranged to be steered by means of a power assistedtransversely mounted element, an actuating rod mounted to said element,the rod arranged for transverse movement, and a flexible coupling meansconnecting said actuating rod to a steerable part of the marinepropulsion unit, so that transverse movement of said element steers thepart of the marine propulsion unit.

Preferably, the element is linked by means of a link to each wheel, thelinks being arranged to fold upwards on refracting the wheels. Both roadand marine steering may be arranged to be operated simultaneously. Thetransversely mounted element may be a rack and pinion steering system.The flexible coupling means is preferably a push-pull cable and a bellcrank means attached to the actuating rod. The actuating rod may bemounted in front of a steering column. The push-pull cable arrangement,comprising a cable slidable in a sleeve, is readily arranged so as tofit between body members and the vehicle power train with a minimumbending radius of 150 mm. In one embodiment, the cable is between 12 and13 mm in diameter, whilst the outer sleeve of the cable is between 15and 17 mm in diameters.

The steering system may be readily adapted to a steering systemcomprising more than one steered front font-axle. It could also beadapted to a marine propulsion system comprising more than one marinepropulsion unit.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will now be described by way of examplewith reference to the following drawings in which:

FIG. 1 is a perspective view from above and behind, of the front wheelsteering arrangement of an amphibian with retractable wheels accordingto the invention;

FIG. 2 is a side view of one front wheel arrangement of the amphibian ofFIG. 1 in road mode, with the front wheel removed for clarity;

FIG. 3 is a side view of the front wheel arrangement of FIG. 2, in thewheel retracted position in marine mode; and

FIG. 4 is a plan view of a marine propulsion unit of the amphibian ofFIG. 1, as steered by the de steering arrangement of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

In the drawings, FIG. 1 shows on the left the front wheel hub assembly 2with brake disc 4 and brake caliper 6. The hub assembly 2 is mounted toupper and lower wishbones 8 and 9, which enable piston and cylinderarrangement 12 to raise the front wheel from the position shown in FIG.2 to that shown in FIG. 3. In doing so, link 14 (there is the samearrangement on the other side, shown at 14′) folds upwards to theposition 14″ shown in broken lines in FIG. 1. (The folded position 14″is shown for link 14′, for clarity). FIG. 3 also shows part of the hull10 to which wishbones 8 and 9 arm mounted via a mounting plate (omittedfor clarity). The hull 10 has a planing bottom 11.

Coupled to links 14 and 14′ is power assisted transversely mountedsteering rack unit 16, actuated by a pinion in housing 18; which in turnis actuated by an inner steering column on axis 20, and finally by asteering wheel 22, shown diagrammatically at a severely reduced scalefor clarity.

The rack movement is some 114 mm lock to lock, whilst the steering wheelhas 2,3 turns from lock to lock. Mounted to rack arm 24 is bracket 26,to which is in turn mounted link rod 28; to the other end of which ismounted bell crank 30. Crank 30 is pivoted about pivot 32, and coupledto push-pull cable 34; which is slidably mounted in flexible casing orsleeve 36. The coupling between rack arm 24 and bell crack 30 is suchthat rod 28 is in front of steering column 20. This ensures economy ofspace.

The rack movement is some 114 mm lock to lock, whilst the steering wheelhas 2,3 turns from lock to lock. Mounted to rack arm 24 is bracket 26,to which is in turn mounted link rod 28; to the other end of which ismounted bell crank 30. Crank 30 is pivoted about pivot 32, and coupledto push-pull cable 34; which is slidably mounted in flexible casing orsleeve 36. The coupling between rack arm 24 and bell crank 30 is suchthat rod 28 is in front of steering column 20. This ensures economy ofspace.

It should be noted that further refinements may be made to the steeringsystem described above without departing from the essential inventiveconcept. For example, the system is particularly suited to be adapted toa road steering system using “steer by wire”; that is, not having amechanical linkage between the steering wheel and the transverselymounted steering element. Such a system would be particularlyadvantageous to a amphibian, in that the bulkhead ahead of the driverwould be more easily sealed against passage of water without aconventional steering column passing therethrough. The power assistedsteering system may be hydraulic, hybrid hydraulic/electric, electric,or magnetic. The input to the marine steering system could be taken froma steered rear axle. This would, however, require some means of controlwhich accounted for the fact that most rear wheel steering systemssometimes steer the rear wheels out of phase with the front wheels; andsometimes in phase with them.

Where two or more marine propulsion units are used, their steeringnozzles may be mechanically linked to ensure that they turn in phasewith each other. Such a linkage may have some geometry comparable toAckermann geometry for road steering. Where two or more front steeredaxles are used, they may both have hydraulic cylinders to steer theirrespective wheels. With two steered front axles and two marine drives, acable could be taken from each steered axle to a respective marinedrive.

The fixing of the cable sleeve to the jet flange described above is asimple and cheap solution. It may be preferred to fix the cable sleeveto a jet flange by means of a bracket and locknuts, thereby allowinglongitudinal adjustment of the cable sleeve; as is known in the marineengineering art.

The steering system described offers a fixed ratio between road andmarine steering, which is fixed at the design stage by the lengths ofthe arms on the bell crank. The drawback of such a fixed ratio isconsidered to be outweighed by the system's compactness, simplicity, andlight weight; each of which are particularly helpful where retractablewheels are fitted.

1. A planing amphibious vehicle comprising: a retractable wheel hubassembly pivotally coupled to the vehicle and configured to be raisedrelative to the vehicle from a road position to a marine position; apower assisted steering unit coupled to the vehicle and comprising asteering arm, wherein the steering arm is actuated by rotation of asteering column to move the steering arm relative to the vehicle, andwherein the steering arm is coupled to the wheel hub assembly andconfigured to permit the wheel hub assembly to be raised from the roadposition to the marine position; a bracket coupled to the steering armand configured to move with the steering arm relative to the vehicle; abell crank pivotally coupled to the vehicle and configured to pivotabout a pivot point; a rod coupling the bracket to the bell crank,wherein the rod transmits the movement of the steering arm to the bellcrank to pivot the bell crank about the pivot point; a marine propulsionunit having a steerable portion pivotally coupled to the vehicle; and acable coupling the bell crank to the steerable portion of the marinepropulsion unit, wherein the cable transmits the movement of the bellcrank to pivot the steerable portion of the marine propulsion unit. 2.The planing amphibious vehicle according to claim 1, wherein the vehiclecomprises at least two retractable wheel hub assemblies pivotallycoupled to the vehicle and configured to be raised relative to thevehicle from a road position to a marine position, and wherein thesteering arm is coupled by means of a link to each wheel hub assembly,the links configured to pivot relative to the steering as each wheel hubassembly is raised from the road position to the marine position.
 3. Theplaning amphibious vehicle according to claim 1, wherein the powerassisted steering unit is a rack and pinion steering system comprising ahousing coupled to the vehicle, a rack arm, and a pinion, and whereinthe pinion is actuated by rotation of the steering column to move therack arm relative to the housing.
 4. The planing amphibious vehicleaccording to claim 1, further comprising at least two axles, each axlecoupled to at least one wheel hub assembly and arranged to be steered bymeans of at least the steering arm.
 5. The planing amphibious vehicleaccording to claim 1, wherein the steering of the wheel hub assembly andthe marine propulsion unit steering are arranged to be operatedsimultaneously using the power assisted steering unit such that thepower assistance to the steering of the wheel hub assembly matches thepower assistance required to overcome the self centering tendency of themarine propulsion unit when running at high speed.
 6. The planingamphibious vehicle according to claim 1, wherein a link couples thesteering arm to the wheel hub assembly, and wherein the link isconfigured to pivot relative to the steering arm as the wheel hubassembly is raised from the road position to the marine position.
 7. Theplaning amphibious vehicle according to claim 1 further comprising atleast a front axle and a rear axle, wherein the steering arm is locatedin front of the front axle of the vehicle.
 8. The planing amphibiousvehicle according to claim 1, wherein the rod is located in front of thesteering column of the vehicle.
 9. The planing amphibious vehicleaccording to claim 1, wherein the length of the rod is adjustable toalign the steering of the wheel hub assembly and the steering of themarine propulsion unit.
 10. The planing amphibious vehicle according toclaim 1, wherein the wheel hub assembly is coupled to the vehicle by anupper wishbone and a lower wishbone.
 11. The planing amphibious vehicleaccording to claim 1, wherein the wheel hub assembly is configured to beraised relative to the vehicle by a piston and a cylinder.
 12. Theplaning amphibious vehicle according to claim 1, wherein the steerableportion of the marine propulsion unit comprises a steering nozzlepivotally coupled to a propulsion conduit housing.
 13. The planingamphibious vehicle according to claim 1, wherein, as the steering armmoves to the left relative to the vehicle, the bell crank pivots in aclockwise direction relative to the vehicle and pulls the cable to pivotthe steerable portion of the marine propulsion unit in a clockwisedirection relative to the vehicle.
 14. The planing amphibious vehicleaccording to claim 1, wherein the cable is a push-pull cable.
 15. Theplaning amphibious vehicle according to claim 14, wherein, as thesteering arm moves to the right relative to the vehicle, the bell crankpivots in a counterclockwise direction relative to the vehicle andpushes the cable to pivot the steerable portion of the marine propulsionunit in a counterclockwise direction relative to the vehicle.
 16. Aplaning amphibious vehicle comprising: a retractable wheel hub assemblypivotally coupled to the vehicle and configured to be raised relative tothe vehicle from a road position to a marine position; a power assistedsteering unit comprising a housing coupled to the vehicle, a rack arm,and a pinion, wherein the pinion is actuated by rotation of a steeringcolumn to move the rack arm relative to the housing; a first linkcoupling the rack arm to the wheel hub assembly, wherein the first linkis configured to pivot relative to the rack arm as the wheel hubassembly is raised from the road position to the marine position; abracket coupled to the rack arm and configured to move with the rack armrelative to the housing; a bell crank pivotally coupled to the vehicleand configured to pivot about a pivot point; a second link coupling thebracket to the bell crank, wherein the second link transmits themovement of the rack arm to the bell crank to pivot the bell crank aboutthe pivot point; a marine propulsion unit having a steerable portionpivotally coupled to the vehicle; and a cable coupling the bell crank tothe steerable portion of the marine propulsion unit, wherein the cabletransmits the movement of the bell crank to pivot the steerable portionof the marine propulsion unit.
 17. The planing amphibious vehicleaccording to claim 16 further comprising at least a front axle and arear axle, wherein the steering arm is located in front of the frontaxle of the vehicle.
 18. The planing amphibious vehicle according toclaim 16, wherein the length of the second link is adjustable to alignthe steering of the wheel hub assembly and the steering of the marinepropulsion unit.
 19. A planing amphibious vehicle comprising: tworetractable wheel hub assemblies coupled to an axle of the vehicle andconfigured to be raised relative to the vehicle from a road position toa marine position, wherein each wheel hub assembly is pivotally coupledto the vehicle by an upper wishbone and a lower wishbone, and whereineach wheel hub assembly is configured to be raised relative to thevehicle by a piston and a cylinder; a power assisted steering unitlocated in front of the axle comprising a housing coupled to thevehicle, a rack arm, and a pinion, wherein the pinion is actuated byrotation of a steering column to move the rack arm relative to thehousing; at least two links coupling the rack arm to each wheel hubassembly, wherein each link is configured to pivot relative to the rackarm as each respective wheel hub assembly is raised from the roadposition to the marine position; a bracket coupled to the rack arm andconfigured to move with the rack arm relative to the housing; a bellcrank pivotally coupled to the vehicle and configured to pivot about apivot point; an actuating rod located in front of the steering columnand coupling the bracket to the bell crank, wherein the actuating rodtransmits the movement of the rack arm to the bell crank to pivot thebell crank about the pivot point; a marine propulsion unit having asteerable portion pivotally coupled to the vehicle, wherein thesteerable portion of the marine propulsion unit comprises a steeringnozzle pivotally coupled to a propulsion conduit housing; and apush-pull cable coupling the bell crank to the steerable portion of themarine propulsion unit, wherein the push-pull cable transmits themovement of the bell crank to pivot the steerable portion of the marinepropulsion unit; wherein the length of the actuating rod is adjustableto align the steering of the wheel hub assemblies and the steering ofthe marine propulsion unit, and wherein the steering of the wheel hubassemblies and the steering of the marine propulsion unit are arrangedto be operated simultaneously using the power assisted steering unitsuch that the power assistance to the steering of the wheel hubassemblies matches the power assistance required to overcome the selfcentering tendency of the marine propulsion unit when running at highspeed.